Method of manufacture of insulation for use in stator slot wedges

ABSTRACT

A slitting and scoring machine includes an upper tooling roller and a lower tooling roller that cooperate to define a tooling nip. Each tooling roller includes an alternating series of coaxially arranged annular knives, annular dies, and annular mandrels. A web of insulation is drawn through the tooling nip to simultaneously (i) cut the web into strips, (ii) score the strips in a manner that promotes the forming of the strips, and (iii) partially form the strips into modified U-shapes. Each strip includes a longitudinally extending middle segment and a pair of longitudinally extending side segments that extend away from the middle segment in a divergent manner to define a longitudinally extending channel. Longitudinally extending grooves are formed by the scoring at the junctures of the middle segment and the side segments. The scoring/grooves promote the divergent shape of the strip. In an end profile view of the strip, the middle segment and each of the side segments are generally straight, and an obtuse angle is defined between each side segment and the middle segment. Each strip is formed into a roll, so that a first length of the strip and a second length of the strip each extend around a common point. At least a portion of the second length is disposed within the channel of the first length.

This invention is a divisional of U.S. application Ser. No. 08/786,259,filed Jan. 22, 1997, now U.S. Pat. No. 5,989,684, which is incorporatedherein by reference.

TECHNICAL FIELD

This invention relates to insulation, and more particularly toinsulation for stator slots in electric motors and generators.

BACKGROUND OF THE INVENTION

Electric motors and generators have many applications. In a typicalmotor or generator, there is a rotor that rotates within a stator. Thestator includes a plurality of fingers that define rotor slotstherebetween. Wires are wound around the fingers and through rotor slotsto define coils. Each coil must be insulated for proper operation.Insulation, in the form of slot wedges, is inserted into the statorslots to insulate coils from the stator.

It is common to create slot wedges from a strip of insulation that isunwound from a roll. Rolled strips are typically created by (i)unwinding a web of sheet-like insulation from a roll, (ii) passing theweb between rolling scissors/knives to cut the web into strips ofinsulation, and (iii) rolling the strips into individual rolls. Then, asa separate step, a rolled strip of insulation is supplied to a machinethat insulates stators. That machine (i) unwinds the strip from itsroll, (ii) cuts the strip into “short” lengths, and (iii) inserts theshort lengths into stator slots. The short lengths are inserted prior tothe installation of the coils onto the stator. During the process ofinserting the short lengths, they become somewhat U-shaped in an endprofile view. Examples of machines that insert slot wedges or insulatingslot cuffs into stator slots are disclosed in U.S. Pat. Nos. 2,340,291;3,616,512; 3,831,255; 3,778,889; 3,778,890; 4,831,716; 4,878,292;4,854,033; and U.S. Pat. No. Re. 34,195.

A common manufacturing defect associated with stators has to do with theinsulation of stator slots. If a stator slot is not properly insulated,the coil therein electrically shorts/fails. While prior methods andapparatus for insulating stator slots are generally effective, thesetype of manufacturing defects still occur, and they typically rendermotors and generators inoperative. Unfortunately, such defects are oftennot detected until stators are completely assembled. It is typicallycost prohibitive to remanufacture a defective stator; therefore, suchdefects result in considerable waste and expense. Even worse, suchdefects are often not detected until after electric motors andgenerators are placed into service.

Accordingly, there is a need for improved methods, apparatus, andarticles of manufacture for forming slot wedges to decreasemanufacturing defects in stators.

SUMMARY OF THE INVENTION

This invention solves the above-described problems in the art byproviding improved methods, apparatus, and articles of manufacture forforming slot wedges to minimize manufacturing defects in stators.Exemplary embodiments of the present invention simultaneously (i) cut aweb of insulation into strips, (ii) score the strips to promote theforming of the strips, and (iii) partially form the strips into modifiedU-shapes. In accordance with a first exemplary embodiment of the presentinvention, the scored and partially U-shaped strips are rolled intorolls. In accordance with a second exemplary embodiment of the presentinvention, the strips are flattened and then rolled into rolls. When therolls of the strips are supplied to a machine that manufactures stators,remarkable savings are achieved because very few of the fabricatedstators have manufacturing defects (i.e., the coils do not electricallyshort/fail).

In accordance with the exemplary embodiments of the present invention, aslitting and scoring machine includes an upper tooling roller and alower tooling roller that cooperate to define a tooling nip. Eachtooling roller includes an alternating series of coaxially arrangedannular knives, annular dies, and annular mandrels. A web of insulationis drawn through the tooling nip where it is formed into a plurality ofscored strips. Each strip is longitudinally extending and has oppositelongitudinally extending edges. While a strip is within the tooling nip,its edges are at least partially bent toward one another so the piece ofinsulation defines a longitudinally extending channel.

Subsequent to exiting the tooling nip, each strip is drawn through adrawing nip defined between drawing rollers. In accordance with thefirst exemplary embodiment, the drawing nip generally maintains theU-shape of the strips. In accordance with the second exemplaryembodiment, the drawing nip flattens the strips. Subsequent to exitingthe drawing nip, each strip is formed into a roll. In each roll, a firstlength of the strip and a second length of the strip extend around acommon point. In accordance with the first exemplary embodiment, atleast a portion of the second length is disposed within the channel ofthe first length.

More particularly, in accordance with the first exemplary embodiment(prior and subsequent to passing through the drawing nip) and the secondexemplary embodiment (prior to being flattened in the drawing nip), eachstrip includes a longitudinally extending middle segment and a pair oflongitudinally extending side segments. The side segments extend awayfrom the middle segment in a divergent manner to define thelongitudinally extending channel. Longitudinally extending grooves aredefined (i.e., formed by scoring) at the junctures of the middle segmentand the side segments. The scoring/grooves promote the divergence of theside segments. In an end profile view of a strip, the middle segment andeach of the side segments are generally straight, and an obtuse angle isdefined between each side segment and the middle segment.

In accordance with the exemplary embodiments, as the web of insulationpasses through the tooling nip, each edge of a strip is cut by aseparate pair of meshing annular knives. For each pair of meshingannular knives, one knife belongs to the upper tooling roller and theother knife belongs to the lower tooling roller. Each strip is at leastpartially shaped in the tooling nip by passing between a die and amandrel that are between the knives that cut the strip. A pair ofannular protrusions on the die score the strip to define the grooves. Inaddition to participating in the cutting, the annular knives that areopposite from the die bend the edges of the strip around the annularprotrusions to form the channel of the strip.

Accordingly, an object of the present invention is to provide improvedmethods, apparatus, and articles of manufacture for forming slot wedgesto minimize manufacturing defects in stators.

Another object of the present invention is to provide a roll of shapedinsulation, where each successive layer nests into the prior layer.

Still another object of the present invention is to decreasemanufacturing defects in stators.

Still another object of the present invention is to minimize waste andexpense associated with manufacturing electric motors and generators.

Other objects, features, and advantages of the present invention willbecome apparent from the following detailed description, drawings, andclaims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic side view of a slitting and forming machine inaccordance with exemplary embodiments of the present invention.

FIG. 2 is a schematic top view of portions of the machine of FIG. 1.

FIG. 3 is a partially cut-away, pictorial view of upper and lowerrotation assemblies of the machine of FIG. 1, with a strip of insulationextending from the tooling nip.

FIG. 4 is a partially cut-away, elevational view of portions of theupper and lower rotation assemblies of FIG. 3.

FIG. 5 is an isolated, partially cut-away, elevational view of a die ofthe rotation assemblies of FIG. 3.

FIG. 6 is an isolated, end profile view of the strip of insulation ofFIG. 3.

FIG. 7 is an isolated, partially cut-away, top plan view of the strip ofinsulation of FIG. 3.

FIG. 8 is a pictorial view of a strip of insulation formed into a roll,in accordance with a first exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION OF DRAWINGS

As summarized above, the present invention provides improved methods,apparatus, and articles of manufacture for forming slot wedges tominimize manufacturing defects in stators. Exemplary embodiments of thisinvention are described in detail below, with reference to drawings inwhich like numbers reference like parts throughout the several views.

Turning now to the drawings, FIGS. 1 and 2 are schematic side and topviews, respectively, of a slitting and forming machine 10 in accordancewith the exemplary embodiments of the present invention. A generallyplanar web 12 of insulation is drawn from a roll 14 that rotates about ashaft 16. The web 12 is drawn through a tooling nip 18 defined betweenan upper rotation assembly (e.g., upper tooling roller 20) and a lowerrotation assembly (e.g., lower tooling roller 22). The tooling rollers20, 22 contemporaneously cut the web 12 into strips 24 a-d, score thestrips 24 a-d, and bend the edges of the strips 24 a-d so that they aregenerally U-shaped, as discussed in greater detail below.

Subsequent to exiting the tooling nip 18, each strip 24 a-d is drawnthrough a drawing nip 25 defined between an upper drawing roller 29 anda lower drawing roller 30. In accordance with a first exemplaryembodiment, each of the drawing rollers 29, 30 has a flexible, somewhatsoft cylindrical surface formed of a material such as, but not limitedto, neoprene; the flexible somewhat soft surfaces of the drawing rollers29, 30 function to grip the strips 24 a-d but do not substantiallyflatten the strips 24 a-d. In accordance with a second exemplaryembodiment, each of the drawing rollers 29, 30 has a more rigidcylindrical surface formed of a material such as, but not limited to,steel or chrome; the rigid surfaces of the drawing rollers 29, 30function to grip and flatten the strips 24 a-d.

Subsequent to exiting the drawing nip 25, the strips 24 a-d are woundinto strip rolls 26 a-d, respectively. Conventional guide plates 27guide the strips 24 a-d to aid in the formation of the strip rolls 26a-d. The strip rolls 26 a, 24 c encircle a driven shaft 40 and the striprolls 26 b, 26 d encircle a driven shaft 41. From the perspective ofFIG. 1, the strip rolls 26 a-d rotate clockwise. This rotation of thestrip rolls 26 a-d draws the strips 24 a-d from the drawing nip 25.

The upper tooling roller 20 and lower tooling roller 22 include and aredriven by a shafts 28, 34, respectively. The upper drawing roller 29 andthe lower drawing roller 30 include and are 30 driven by shafts 32, 36,respectively. From the perspective of FIG. 1, the upper tooling roller20 and the upper drawing roller 29 rotate counterclockwise. From theperspective of FIG. 1, the lower tooling roller 22 and the lower drawingroller 36 rotate clockwise. The rotation of the rollers 20, 22, 29, 30unwinds the web 12 from the roll 14 and draws the web 12 through thenips 18, 25.

The shafts 28, 32, 34, 36, 40, 41 are driven by the output shaft of amotor 38, in a conventional manner. An endless drive element, such as adrive belt 35, which is partially cut-away in FIG. 1, extends betweenthe output shaft of the motor 38 and a pulley (not shown) carried by theshaft 36 to drive the lower drawing roller 30. A gear (not shown)carried by the shaft 36 meshes with a gear (not shown) carried by theshaft 32 to drive the upper drawing roller 29. A gear (not shown)carried by the shaft 34 meshes with an idler gear 37 and the gear (notshown) carried by the shaft 36 to drive the lower tooling roller 22. Agear (not shown) carried by the shaft 28 meshes with the gear (notshown) carried by the shaft 34 to drive the upper tooling roller 20. Anendless drive element, such as a drive chain 39, which is partiallycut-away in FIG. 1, extends between a sprocket (not shown) carried bythe shaft 36 and a sprocket (not shown) carried by the shaft 40 to drivethe strip rolls 26 a, 26 c. An endless drive element, such as a drivechain 42, which is partially cut-away in FIG. 1, extends between asprocket (not shown) carried by the shaft 40 and a sprocket (not shown)carried by the shaft 41 to drive the strip rolls 26 b, 26 d.

The slitting and forming machine 10 includes a conventional mechanism(not shown) for separating the tooling rollers 20, 22 and the drawingrollers 29, 30 to widen the tooling nip 18 and the drawing nip 25,respectively. This facilitates the initial insertion of the web 12 intothe tooling nip 18 and drawing nip 25. The same mechanism also forcesthe tooling rollers 20, 22 toward one another into a meshedconfiguration that is operative to form the strips 24 a-d from the web12.

FIG. 3 is a partially cut-away, pictorial view of the upper and lowertooling rollers 20, 22 with a single strip 24 a extending from thetooling nip 18 for illustrative purposes. FIG. 4 is a partially cutaway,elevational view of portions of the upper and lower tooling rollers 20,22. The upper tooling roller 20 includes annular knives 46 a-e, annulardies 48 a-b, and annular mandrels 50 a-b, all of which define axiallyextending central bores through which the shaft 28 is press-fit. Theknives 46 a-e, dies 48 a-b, and mandrels 50 a-b are fixed to the shaft28 and rotate coaxially therewith about the axis 52. Similarly, thelower tooling roller 22 includes annular knives 46 f-j, annular dies 48c-d, and annular mandrels 50 c-d, all of which define axially extendingcentral bores through which the shaft 34 is press-fit. The knives 46f-j, dies 48 c-d, and mandrels 50 c-d are fixed to the shaft 34 androtate coaxially therewith about the axis 54.

Each of the knives 46 a-j is identically constructed. Each knife 46 is aright circular cylinder having a diameter of approximately 3.250 inches,an axial length of approximately 0.025 inches, and a centered axiallyextending bore for receiving one of the shafts 28, 34, as discussedabove. Each of the mandrels 50 a-d is identically constructed. Eachmandrel 50 is a right circular cylinder having a diameter ofapproximately 3.200 inches, an axial length of approximately 0.211inches, and a centered axially extending bore for receiving one of theshafts 28, 34, as discussed above.

Each of the dies 48 a-d is identically constructed. FIG. 5 is anisolated, partially cut-away, elevational view of a die 48. Each die 48is uniform around its periphery. Each die 48 includes an annular centralsurface 56 that is in the form of a right circular cylinder that iscoaxial with the axis of the die 48. The central surface 56 has adiameter of approximately 3.200 inches and an axial length ofapproximately 0.1140 inches. Each die 48 includes a first annularprotrusion 58 at one side of the central surface 56 and a second annularprotrusion 60 at the opposite side of the central surface 56. A channelsurface 66 extends between the first protrusion 58 and a side surface62. Likewise, channel surface 68 extends between the second protrusion60 and a side surface 64. Each annular protrusion 58, 60 is generallyidentical, each side surface 62, 64 is generally identical, and eachchannel surface 66, 68 is generally identical; therefore a discussion ofone should be understood to refer to the other.

The first annular protrusion 58 is coaxial with the axis of the die 48and includes an annular cylindrical surface 65 at its apex.

The cylindrical surface 65 is coaxial with the axis of the die 48 andhas a diameter of approximately 3.2 inches and an axial length ofapproximately 0.01 inches. The first annular protrusion 58 furtherincludes a first sloping surface 67 that is coaxial with the axis of thedie 48. The first sloping surface 67 extends from an edge of the annularcylindrical surface 65 to the edge of the central surface 56 at an angleof approximately 45 degrees relative to the cylindrical surface 65. Thefirst annular protrusion 58 further includes a second sloping surface 69that is coaxial with the axis of the die 48. The second sloping surface69 extends from an edge of the cylindrical surface 65 to the upper edgeof the channel surface 66 at an angle of approximately 45 degreesrelative to the cylindrical surface 65. Each of the sloping surfaces 67,69 extend approximately 0.005 inches in the axial direction. The sidesurface 62 is planar and perpendicular to the axis of the die 48. Thechannel surface 66 slopes upward from the side surface 62 at an angle ofapproximately 30 degrees relative to the side surface 62 (i.e., relativeto a vertical reference). The axial distance between the side surfaces62, 64 is approximately 0.2613 inches. Each die 48 defines a centered,axially extending bore for receiving one of the shafts 28, 34 (FIGS. 1and 3), as discussed above.

In accordance with the exemplary embodiments of the present invention,the tooling rollers 20, 22 are meshed in the manner depicted in FIG. 4when the slitting and forming machine 10 (FIGS. 1 and 2) is forming theweb 12 (FIGS. 1 and 2) into strips 24 a-d (FIGS. 13). In the uppertooling roller 20, the knife 46 a abuts the die 48 a, which abuts theknife 46 b, which abuts the mandrel 50 a, which abuts the knife 46 c,which abuts the die 48 b, which abuts the knife 46 d, which abuts themandrel 50 b, which abuts the knife 46 e. Stated differently, the knives46 a, 46 b sandwich the die 48 a; the knives 46 b, 46 c sandwich themandrel 50 a; the knives 46 c, 46 d sandwich the die 48 b; and theknives 46 d, 46 e sandwich the mandrel 50 b.

In the lower tooling roller 22, the knife 46 f abuts the mandrel 50 c,which abuts the knife 46 g, which abuts the die 48 c, which abuts theknife 46 h, which abuts the mandrel 50 d, which abuts the knife 46 i,which abuts the die 48 d, which abuts the knife 46 j. Stateddifferently, the knives 46 f, 46 g sandwich the mandrel 50 c; the knives46 g, 46 h sandwich the die 48 c; the knives 46 h, 46 i sandwich themandrel 50 d; and the knives 46 i, 46 j sandwich the die 48 d.

Regarding the tooling rollers 20, 22 together, the peripheries of theknives 46 a, 46 f overlap so that sides of those knives 46 a, 46 f arein contact. The peripheries of the knives 46 b, 46 g overlap so thatsides of those knives 46 b, 46 g are in contact. The peripheries of theknives 46 c, 46 h overlap so that sides of those knives 46 c, 46 h arein contact. The peripheries of the knives 46 d, 46 i overlap so thatsides of those knives 46 d, 46 i are in contact. And, the peripheries ofthe knives 46 e, 46 j overlap so that sides of those knives 46 e, 46 jare in contact. The die 48 a is above and faces the mandrel 50 c. Thedie 48 b is above and faces the mandrel 50 d. The die 48 c is below andfaces the mandrel 50 a. And, the die 48 d is below and faces the mandrel50 b.

The relationship between the knives 46 associated with each facing die48 and mandrel 50 pair is the same, so a discussion of the interactionbetween the knives 46 a, 46 b, 46 f, 46 g associated with the die 48 aand the mandrel 50 c should be understood to be representative. Theknife 46 a has an inner side that is contacting the die 48 a and anouter side that is opposite from the die 48 a. Similarly, the knife 46 bhas an inner side that is contacting the die 48 a and an outer side thatis opposite from the die 48 a. The knife 46 f has an inner sidecontacting the mandrel 50 c and an outer side that is opposite from themandrel 50 c. Similarly, the knife 46 g has an inner side that iscontact the mandrel 50 c and an opposite outer side that is oppositefrom the mandrel 50 c. The knives 46 a, 46 f overlap such that the innerside of the knife 46 a contacts the outer side of the knife 46 f.Similarly, the knives 46 b, 46 g overlap such that the inner side of theknife 46 b contacts the outer side of the knife 46 g.

As described above and depicted in FIG. 4, the meshing of the toolingrollers 20, 22 segments the tooling nip 18 into generally identicaltooling nip sections 18 a-d, within which the strips 24 a-d are formed,respectively. Due to the similarity between tooling nip sections 18 a-d,the following discussion of tooling nip section 18 a should beunderstood to be representative of the other tooling nip sections 18b-d. In the tooling nip section 18 a, the distance between the centralsurface 56 (FIG. 5) of the die 48 a and the peripheral surface of themandrel 50 c is approximately 0.015 inches, which approximatelycorresponds to the thickness of the web 12 (FIG. 1). The tooling nipsection 18 a includes a channel 70 defined between the knife 46 a andthe channel surface 66 (FIG. 5) of the die 48 a. The tooling nip section18 a also includes a channel 72 defined between the knife 46 b and thechannel surface 68 of the die 48 a.

As the web 12 (FIGS. 1 and 2) passes through the tooling nip section 18a, the interaction between the knives 46 a, 46 f cut one side of thestrip 26 a (FIGS. 1-3), and the interaction between the knives 46 b, 46g cut the other side of the strip 26 a. Simultaneously with the cutting,the protrusions 58, 60 (FIG. 5) of the die 48 a score the strip 26 a,and the periphery of the knives 46 f, 46 g and the mandrel 50 c forcethe strip 26 a against the surfaces of the die 48 a that are exposedwithin the tooling nip section 18 a. Therefore, the strip 26 a takes onthe shape of the surfaces of the die 48 a that are exposed within thetooling nip section 18 a. While the slitting and forming machine 10(FIGS. 1 and 2) is characterized herein as including only four toolingnip sections 18 a-d and creating only four strips 24 a-d (FIG. 1), it ispreferable for the machine 10 to include additional tooling nip sectionsand accommodate for additional strips, in a manner that would beunderstood by those skilled in the art upon understanding thisdisclosure.

Referring to FIG. 4, in accordance with an alternative embodiment of thepresent invention, the surface of each of the mandrels 50 a-d ismodified to include a pair of annular grooves that are for receiving thepair of protrusions 60 on the dies 48 a-d, respectively. As arepresentative example, a pair of annular grooves 44, 45 are depicted inbroken lines on the mandrel 50 d in FIG. 4. Having the protrusions 60protrude into the grooves 44, 45 aids in the formation of strips 26,especially when the strips 24 a-d are a material that is relatively hardto form.

Each of the strips 24 a-d (FIG. 2) are generally identical. FIG. 6 is anisolated, end profile view, and FIG. 7 is an isolated, partiallycut-away, top plan view of a strip 24 subsequent to exiting the toolingnip 18 (FIG. 1) and prior to entering the drawing nip 25 (FIG. 1). Thestrip 24 includes a longitudinally extending middle segment 74 andlongitudinally extending side segments 76, 78 that extend upward fromthe middle segment 74 in a divergent manner. Angles “A1” and “A2” aredefined between the middle segment 74 and the side segments 76, 78,respectively. The angles “A1” and “A2” are preferably oblique for astrip 24 that has exited the tooling nip 18 (FIG. 1) and has not yetentered the drawing nip 18.

As depicted in FIGS. 6 and 7, the internal surfaces of the segments 74,76, 78 cooperate to define a longitudinally extending channel 80. Theexternal surfaces of the segments 74, 76, 78 are opposite from thechannel 80. The strip 24 defines longitudinally extending grooves 79, 81formed by the scoring action of protrusions 58, 60 (FIG. 5),respectively. The first groove 79 is collinear with the juncture of thesegments 74, 76, and the second groove 81 is collinear with the junctureof the segments 74,78. Each groove 79, 81 can be characterized asincluding a plurality of indentations that are so numerous and proximatethat a generally continuous and uniform groove is defined. The strip 24is continuous, generally uniform along its length, and unitary (meaningthat it is absent of separate but joinable parts).

In accordance with the exemplary embodiments of the present invention,subsequent to exiting the drawing nip 18 (FIG. 1), the angles “A1” and“A2” each acceptably range from between approximately 95 degrees to 180degrees. For a given strip 24, each of the angles “A1” and “A2” arepreferably approximately identical. In accordance with the firstexemplary embodiment, where each of the drawing rollers 29, 30 (FIG. 1)preferably has a flexible, somewhat soft surface, the drawing nip 25(FIG. 1) generally does not change the shape of the strips 24 passingtherethrough. That is, the angles “A1” and “A2” of a strip 24 passingthrough the drawing nip 25 are substantially unchanged, in accordancewith the first exemplary embodiment.

In accordance with the second exemplary embodiment, where each of thedrawing rollers 29, 30 (FIG. 1) preferably has a surface that is morerigid than in the first exemplary embodiment, the drawing nip 25(FIG. 1) does change the shape of the strips 24 passing therethrough.That is, in accordance with the second exemplary embodiment, the strips24 are at least partially flattened (i.e., the angles “A1” and “A2” areincreased) as they pass through the drawing nip 25. For example, inaccordance with the second exemplary embodiment, the angles “A1” and“A2” can be 180 degrees. When the hardness of the surfaces of thedrawing rollers 29, 30 is increased, the strips 24 become flatter, andwhen the hardness of the surfaces of the drawing rollers 29, 30 isdecreased, the flattening of the strips 24 decreases.

In accordance with the first exemplary embodiment, the strip rolls 26a-d (FIG. 2) are generally identical. FIG. 8 is a pictorial view of astrip 24 formed into a roll 26, in accordance with the first exemplaryembodiment. The strip 24 depicted in FIG. 8 is continuous (i.e.,unbroken) intermediate of its ends 83, 85. The strip 24 includes lengths84, 86, 88, 90, 92, 94, 96 which are generally concentric and extendaround a central point (i.e., a point on the axis of the tube 82) forapproximately 360 degrees. The outer surface of the middle segment 74 ofthe first length 84 abuts the outer surface of the tube 82 forapproximately 360 degrees. The outer surface of the middle segment 74 ofthe second length 86 abuts the inner surface of the middle segment 74 ofthe first length 84 for approximately 360 degrees. A substantial portionof the outer surfaces of the side segments 76, 78 of the second length86 abut the inner surfaces of the side segments 76, 78, respectively, ofthe first length 84 for approximately 360 degrees. Therefore, asubstantial portion of the second length 76 is within the channel 80 ofthe first length 84 for approximately 360 degrees. Each successivelength of the strip 24 similarly nests into the channel 80 of the priorlength of the strip 24.

In accordance with the second exemplary embodiment, the strip rolls 26a-d (FIG. 2) are also generally identical. In accordance with the secondexemplary embodiment, a roll 26 would be identical to that which isdepicted in FIG. 8, except that the angles “A1” and “A2” (FIG. 6) wouldbe greater than that which is depicted in FIG. 8. For example, inaccordance with one acceptable example of the second exemplaryembodiment, the angles “A1” and “A2” can be 180 degrees, such that aroll includes a continuous flat strip 24 wrapped generallyconcentrically around a central point (i.e., a point on the axis of atube 82). In summary, in accordance with the exemplary embodiments ofthe present invention, for a roll 26, each of the angles “A1” and “A2”(FIG. 6) are preferably approximately identical and acceptably rangefrom between approximately 95 degrees to 180 degrees.

In accordance with the exemplary embodiments, the web 12 (and thereforethe strips 24 a-d) is preferably insulation such as: high temperaturearamid paper, such as that sold under the trademark “NOMEX”; hardvulcanized fiber; “MYLAR”; polyester fiber paper saturated with a heatresistant epoxy resin, such as that sold under the trademark “DUROID”;or laminate of “DACRON” and polyester film. These insulations areavailable from Fabrico, a division of Electrical Insulation Suppliers,Inc., which has facilities, for example, in Atlanta, Ga.; Mequon, Wis.;and Rancho Cucamonga, Calif.

In accordance with one acceptable example, subsequent to passing throughthe drawing nip 25 (FIG. 1) a strip 24 of vulcanized fiber has angles“A1” and “A2” (FIG. 6) which are each approximately identical andapproximately 168 degrees to 165 degrees. In accordance with anotheracceptable example, subsequent to passing through the drawing nip 25(FIG. 1) a strip 24 in the form of a layer of “MYLAR” sandwiched (e.g.,laminated) between an upper layer of “DACRON” and a lower layer of“DACRON” has angles “A1” and “A2” (FIG. 6) which are each approximatelyidentical and approximately 175 degrees to 174 degrees.

Referring to FIGS. 1 and 6, in accordance with the exemplaryembodiments, when all other variables are held constant, the angles “A1”and “A2” can be varied by varying the material of the web 12 (andtherefore the strips 24 a-d). For example, when the strips 24 a-d are amaterial that is relatively harder to form (e.g., a “DACRON” /“MYLAR”/“DACRON” laminate) the angles “A1” and “A2” angle will be greater thanwhen the strips 24 a-d are a material that is relatively easier to form(e.g., a paper that is not laminated). Other examples of means forvarying the angles “A1” and “A2” are outlined below.

Referring to FIGS. 1, 5, and 6, in accordance with the exemplaryembodiments, when all other variables are held constant, the angles “A1”and “A2” can also be varied by varying the angle that channel surface 66slopes upward from the side surface 62. As depicted in FIG. 5, thisangle (i.e., the angle of the channel surface 66) is approximately 30degrees relative to the side surface 62 (i.e., relative to a verticalreference). Increasing the angle of the channel surface 66 tends toincrease the angles “A1” and “A2”, while decreasing the angle of thechannel surface 66 tends to decrease the angles “A1” and “A2”.

Referring to FIGS. 1, 4, and 6, in accordance with the exemplaryembodiments, when all other variables are held constant, the angles “A1”and “A2” can also be varied by varying the shape of the knives 46. Forexample, increasing the diameter of the knives 46 tends to decrease theangles “A1” and “A2”, while decreasing the diameter of the knives 46tends to increase the angles “A1” and “A2”. Similarly, increasing anddecreasing the width (i.e., axial length) of the knives 46 will decreaseand increase, respectively, the angles “A1” and “A2”.

It should be understood that, throughout this disclosure, unlessindicated otherwise, details provided apply to both the first exemplaryembodiment and the second exemplary embodiment. Also, the secondexemplary embodiment is generally identical to the first exemplaryembodiment, unless indicated otherwise. It should also be understoodthat the foregoing relates to particular embodiments of the presentinvention, and that numerous changes may be made therein withoutdeparting from the scope of the invention as defined by the followingclaims.

We claim:
 1. A method of forming insulation, comprising the steps of:shaping a longitudinally extending strip having opposite longitudinallyextending edges, comprising the steps of bending the edges toward oneanother so that the strip defines a longitudinally extending channel,and scoring the strip in a manner that promotes the bending step,wherein the scoring step and the bending step are contemporaneous. 2.The method of claim 1, wherein the shaping step further comprising thestep of slitting a web to form the strip, wherein the steps of slitting,bending, and scoring are contemporaneous.
 3. The method of claim 2,further comprising the steps of: unrolling the web from a roll; drawingthe web through a nip, wherein the shaping step is carried out in thenip; and forming the strip into a roll such that a first length of thestrip and a second length of the strip each extend around a common pointand at least a portion of the second length is disposed within a channelof the first length.
 4. The method of claim 3, wherein the nip isdefined between a pair of meshing rotation assemblies, each rotationassembly comprising an alternating series of coaxially arranged annularknives, annular dies, and annular mandrels.
 5. The method of claim 1,wherein the bending step comprises the steps of forming a longitudinallyextending first juncture between a longitudinally extending first sidesegment of the strip and a longitudinally extending middle segment ofthe strip, and forming a longitudinally extending second juncturebetween the middle segment and a longitudinally extending second sidesegment of the strip, and wherein the scoring step comprises the stepsof forming a first plurality of indentations extending longitudinallyand proximate to the first juncture, and forming a second plurality ofindentations extending longitudinally and proximate to the secondjuncture.
 6. The method of claim 5, wherein the first plurality ofindentations are closely arranged such that the piece of insulationdefines a first longitudinally extending groove that is generallycollinear with the first juncture, and wherein the second plurality ofindentations are closely arranged such that the piece of insulationdefines a second longitudinally extending groove that is generallycollinear with the second juncture.
 7. The method of claim 1, whereinthe shaping step is a first shaping step, and wherein the method furthercomprises a second shaping step comprising a step of at least partiallyflattening the strip.
 8. A method of transforming a web of insulation,comprising the steps of: forming a strip, comprising the steps ofslitting the web to form a longitudinally extending strip havingopposite longitudinally extending edges, and bending the edges towardone another such that the strip defines a longitudinally extendingchannel, wherein the slitting step and the bending step arecontemporaneous.
 9. The method of claim 8, further comprising the stepof contemporaneously creating a plurality of strips from the web byperforming the forming step for each strip of the plurality of strips.10. The method of claim 8, further comprising the steps of: unrollingthe web from a roll; drawing the web through a nip, wherein the formingstep is carried out in the nip; and forming the strip into a roll suchthat a first length of the strip and a second length of the strip eachextend around a common point and at least a portion of the second lengthis disposed within a channel of the first length.
 11. The method ofclaim 10, wherein the nip is defined between a pair of meshing rotationassemblies, each rotation assembly comprising an alternating series ofcoaxially arranged annular knives, annular dies, and annular mandrels.12. The method of claim 8, wherein the forming step further comprisingthe step of scoring the strip in a manner that promotes the bendingstep.
 13. The method of claim 12, wherein the bending step comprises thesteps of forming a longitudinally extending first juncture between alongitudinally extending first side segment of the strip and alongitudinally extending middle segment of the strip, and forming alongitudinally extending second juncture between the middle segment anda longitudinally extending second side segment of the strip, and whereinthe scoring step comprises the steps of forming a first plurality ofindentations extending longitudinally and proximate to the firstjuncture, and forming a second plurality of indentations extendinglongitudinally and proximate to the second juncture.
 14. The method ofclaim 13, wherein the first plurality of indentations are closelyarranged such that the piece of insulation defines a firstlongitudinally extending groove that is generally collinear with thefirst juncture, and wherein the first plurality of indentations areclosely arranged such that the piece of insulation defines a firstlongitudinally extending groove that is generally collinear with thefirst juncture.
 15. The method of claim 8, further comprising a step ofat least partially flattening the strip subsequent to the forming step.